Boot upper



FIG. 1 is a perspective view of a boot upper according to my new design;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a top plan view thereof.

All of the dashed lines in FIGS. 1 to 6 are included for the purpose of illustrating stitching and form a part of the claimed design. All of the phantom lines in FIGS. 1 to 5 are included for the purpose of illustrating environmental structure and form no part of the claimed design. 

The ornamental design for a boot upper, as shown and described. 